Created by Michel Montignac who put a base of a diet around a foods glycemic index or GI. The higher the GI rating of a particular food, the worse it is for you. On the contrary of low carb, low fat or low calorie diet, chocolate addicts can still indulge as long as it's dark and the odd piece of bread isn't completely forbidden.

The diet is split in to two phases, Weight Loss and Weight Maintenance. The first phase is a kind of detox period, which means that it's pretty strict for the first two months but the meals won't leave you starving unlike most fad diets. The second phase is more tolerant, allowing you to spread your dietary wings a little and let more foods back in to your fridge while still following the method and keeping your weight at the level you want.

Phase I:

This phase consists chiefly of eating the appropriate carbs, namely those with glycemic index ranked at 35 or lower. A higher protein intake, especially from fish and legumes, can help weight-lose.

"Bad carbohydrates", such as those in sweets, potatoes, rice, and white bread, may not be taken together with fats, especially during Phase 1 of the method. According to Montignac's theory, these combinations will lead to the fats in the food being stored as body fat. Some kinds of pasta, such as "al dente" durum wheat spaghetti, some varieties of rice, such as long-grain Basmati, whole grains and foods rich in fiber, have a not so high GI.

Phase 1 is the rapid weight loss phase. In this phase, people eat normal quantities of food in balanced meals. However, their choice of foods is restricted low glycemic index ones (which have the smallest impact on insulin secretion). Once they have succeeded in losing weight, they can switch to the Phase 2, which is the weight control phase.

Phase II:

"We can even enhance our ability to choose -says Montignac- by applying a new concept, the glycemic outcome (synthesis between glycemic index and pure carbohydrate content) and the blood sugar levels which result from the meals. Under these conditions, we can eat whatever carbohydrate we want, even those with high glycemic indexes".

Phase 2 also limits food choices. However, the range of permitted foods is much wider. High glycemic index foods are permitable in Phase 2, provided that low glycemic index foods are also eaten during the same meal as compensation.

The Montignac method is concentrated on 'good' and 'bad' sides of each food group, not cutting a necessary group out completely.

What is Glycemic Index?

Foods only appear on the glycemic index if they contain carbohydrate. This explains why you won't find foods like fresh meat, chicken, fish, eggs and cheese in GI lists.

The Glycemic index or GI is a measure of the effects of carbohydrates on blood glucose levels. Carbohydrates that break down rapidly during digestion releasing glucose rapidly into the bloodstream have a high GI; carbohydrates that break down slowly, releasing glucose gradually into the bloodstream, have a low GI. For most people, foods with a low GI have significant health benefits.

The GI diet is all about insulin and controlling blood sugar levels. Insulin is a hormone which helps regulate our blood sugar; actually it lowers blood sugar levels by stimulating cells to absorb any excess sugar from the blood. The problem with insulin is it also causes fat cells to take up excess fatty acids from the blood.

There is an established theory that if one can control insulin levels then one can control how much fat the body will store from each and every meal. Fat can only be stored when insulin is present, and insulin is only released when blood sugar levels become elevated.

Carbohydrate in foods will raise blood sugar if it is absorbed too rapidly. The types of foods which cause rapid absorption of sugar are all those with a high GI index rating. The GI ranks carbohydrate foods by assigning them a number ranging from 0 to 100. The number indicates the rate at which the food raises blood glucose levels during its absorption. The higher the value the quicker the sugar is absorbed.

A high GI food has a value of 70 and above. A GI value of 56-69 is considered medium and any foods lower than 55 are considered a low GI food. Foods with a low GI are best as they digest more slowly and naturally and help provide a steady supply of energy over the course of several hours, it also makes us feel fuller for longer. High GI foods break down very quickly in the body and make you feel hungry again soon after consuming them.

High GI, but good

There are some foods which have a high GI rating but are considered a healthy nutritious food. In these cases healthy high GI foods can be combined with low GI foods to maintain low-medium GI value, plus help create a complete nutritional intake. An example is baked potato (high GI) topped with baked beans (low GI). There are also low GI foods which should be limited. Fresh meat and poultry contains no sugar so the GI will be very low, however, they do contain lots of fat and protein so the energy content will be high. Remember calories do still count!

Factors Affecting Glycemic Index

A number of factors determine a food's glycemic index. One of the most important is how highly processed the carbohydrates are. Whole-grain foods tend to have a lower glycemic index than their refined products. For example, white rice, which its bran and germ have been removed, has a higher glycemic index than brown rice, which is less processed.

Other Factors affecting Glycemic Index:

- Fiber content:
Fiber, especially soluble fiber, slows down the digestion of starch, therefore high fiber foods have lower glycemic index. For instance, apples with skin have a lower glycemic index than apples without skin.

- How much fibre does it contain?
Fibre slows the time it takes the body to break down a food. This is one reason why beans and pulses (which are wrapped in a fibrous shell) have such a low GI.

- How much starch does it contain, and in what form?
The easiest ingredient for our body to convert into glucose is starch. When foods are raw, this starch is generally found in hard, compact particles that the body finds hard to break down. However, if something disturbs these starch particles (e.g. milling into flour), the body finds it much easier to digest them and they turn into glucose faster.

- Fat, Protein:
Fat and protein slow down foods from leaving the stomach, therefore foods containing fat and protein such as beans and milk have lower glycemic index values.

- Does it contain fat?
As well as having no effect on glucose itself, fat slows the speed at which food leaves the stomach and reaches the liver, slowing glucose production. This is the reason why potato crisps have a lower Gl than most other types of potato.

- Does it contain carbohydrate?
Pure protein foods such as meat, fish, poultry and eggs, and pure fats such as oils, butter and margarine, contain no carbohydrate. As a result, the effect they have on glucose production is negligible. These foods are therefore low Gl.

- What kind of sugar does it contain?
There are four main types of sugar, and they raise blood sugar levels at different rates. Foods with a high concentration of glucose (such as sports drinks) need no conversion, so they raise blood sugar rapidly. Fructose (the sugar in fruit), however, converts slowly; as does lactose which is the main sugar in dairy products. This gives the majority of foods containing either fructose or lactose a low Gl. The fourth sugar, sucrose, has a medium Gl.

- Acid content:
Lemon juice or vinegar can also lower the glycemic index.

- How acidic it?
Foods can contain acid ingredients - citrus fruits like oranges or lemons are a good example of this. The tang they create on your tongue comes from the citric acid they contain. Other acidic ingredients include lactic acid in milk products, and added ingredients, such as vinegars, in pickled products, just like fat, acidity slows a food's progress through the system, and therefore slows the rate at which it converts into glucose.

- Maturation:
Unripened fruits have lower glycemic index values than ripe fruits.

Examples

Low GI (GI range 55 or less):

most fruit and vegetables (except potatoes, watermelon), grainy breads, pasta, legumes/pulses, basmati rice, milk, products extremely low in carbohydrates (fish, eggs, meat, nuts,oils)

Medium GI (GI range 56 - 69):

wheat bread, whole wheat products in general, brown rice, orange sweet potato, table sugar

High GI (GI range 70 - 99):

corn flakes, baked potato, some white rices (eg. jasmine), croissant, white bread, candy

GI 100:
straight glucose

Calorie intake is not responsible for fat storage. If we put on weight it is not because we eat too much but because we eat wrongly. The nature of the food we eat stimulates metabolic reactions leading to fat storage instead of fat burning. Although this applies to all food categories, the choice of carbohydrates is particularly decisive.

These statistics prove that low-calorie diets are a total failure. Low-calorie-diets actually slow down the metabolism. This reduced basal metabolic rate leaves the body vulnerable to rapid and excess weight gain once the person comes off the low-calorie diet.

THE DIET'S GOLDEN RULE

is to eat as low on the glycaemic index as possible, in order to trigger fat loss. Most overweight people release too much insulin when they eat carbohydrates, and the stored glucose is then converted into fat. Low GI foods stabilize the amount of insulin that is produced by the pancreas, which, in turn, improves the efficiency of your metabolism to allow you to maintain the weight loss. Montignac also believes the diet is successful because it allows you to eat the foods you love, so it is sustainable - even over Christmas.

Sample menu

The menus give two main meal options: either protein and fat, or high-fibre carbohydrate. Lunch should be the main meal of the day.

Breakfast: herbal or fruit tea; oatcakes topped with non-fat cheese; and sliced apples.

Lunch: cherry tomato and basil soup; chef salad of cheese, ham, boiled egg, tomatoes and olive oil; and a few squares of dark chocolate. Optional snack: almonds and hazelnuts.

Dinner: vegetable soup; wild mushroom ramekins with rocket salad; chopped apples with fromage frais.

The great news is, that although cabbage and lettuce obviously have the lowest GI, there are some lovely surprises like peanuts being lower than lentils, cookies below raisins and rice cakes being a whole fifty points more than vanilla ice cream.

The plans take inspiration from French cuisine, so the good news is that the foods that are blacklisted by calorie-counting diets - such as red wine, cheese and chocolate - are all allowed.

Definitely a diet to stick to!